I have a e350 2007 my engine cranks but would not start. Left the car for a few hours sometimes day then it would start. Drives well with no sputter, no hesitation, no backfire but sometimes when I stop it wont start for a few hours. changed the CPS senor 3time and starts right up when I do but when I drive for a while it cranks but wont start. I put the old CPS sensor back in and started right up, but same happens when I stop and turn off car. Dealer says new Fuel pump but it just does not seem like that is the problem. Any Ideas

a relay?

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1999 w140, quit voting to old, and to old to fight, a god damned veteran, deutschland deutschland uber alles uber alles in der welt

The easy stuff always first. Had a very similar problem with a Volvo, got a new battery and solved the problem. When the fuel pump goes bad you will hear it is my experience.

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1979 Black on Black, 300CD (sold), 1990 Black 300SE, Silver 1989 Volvo 780, 1988 300CE (vanished by the hands of a girlfriend), 1992 300CE (Rescue).

bbarnes, when was the fuel filter replaced last? Fuel filter replacement should be done every 60,000 miles. If the fuel pump was shot the engine would never start.

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Fred Hoelzle

Thank you all for your input. I bought the car used 4 years ago and put about 50K on it. When it had a 108k on it. The dealer (same dealer that said the Fuel pump was bad) stated they did a extensive service on it so they may have changed the filter. I changed the Fuel pump relay last night and drove it to work today so I will watch it for a few days to see if it does the same thing again. I plan to change fuel filter today (just to be on the safe side). The DEALERSHIP was trying to charge me $1300.00 to change a fuel filter and if I prove they were lying, all hell going to break loose, I will but this on all the news channels.

We'll be huddled around our TV's with baited breath...

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Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]

If the 211 is like the 210, there’s a check valve in the fuel pump that goes bad. The pump itself is fine but the system can’t hold static pressure causing difficult starts. Check fuel rail pressure before you start. For the 210, the ~$20 Harbor Freight kit that says it doesn’t work for MB or Bosch does. It’s CIS it doesn’t support.

Sixto
98 E320s sedan and wagon

First of all I have driving E' classes for over 30years and I had no idea they are also called 211 or 210 thanks for the enlightenment. Thanks, for the input. In your experience would the car drive very well despite this bad valve. Also can this valve be replaced without replacing the pump.

To be clear, the W210 was sold in the US in the 96-02 (‘03 wagon) model years. The W211 was sold in the 03-09 model years.

In the 210, the check valve an integral part of the pump. You toss a good pump to replace the check valve. A bad check valve only affects starting. The engine runs fine once system pressure is up. Starting is difficult because the sequence runs the pump for a couple of seconds then waits for an rpm threshold to run the pump again. In a 210 you can turn the key from off to run without hitting the starter a few times to build pressure. I don’t think there’s an equivalent with a keyless system.

Sixto
98 E320s sedan and wagon

Sixto - You toss a good pump to replace the check valve. Not sure what this means???

Thx

Thanks Sixto. Just to let everyone know the relay did not work. Based on what you said, if I turn key to on position a few times to build up pressure and then turn key fully to start then the car should start. Worth a try. As for having to throw out a good pump because the check valve well that's a just messed up. If this works then I guess I cant slam that dealership. I will keep you all posted

bbarnes39, I just looked at the fuel filter for your 2007 E350 and it's a part that I have never seen before. It looks like it attaches to the fuel tank relying on seals/O-rings to prevent leaks. I can understand why it would be more costly to replace that style fuel filter, but not to the tune of $1,300. The 60,000 mile fuel filter replacement interval I mentioned previously was for a canister style fuel filter. I should not have given any advice about the newer style fuel filter on your 2007 E350. I apologize.

The fuel pump assembly for your 2007 E350 is different from any MB fuel pump I have ever seen. Replacement is likely more difficult than on the older MB vehicles that I own.

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Fred Hoelzle

I mean because the 210 check valve is part of the fuel pump, if the check valve goes bad, you have to replace the entire fuel pump assembly including an otherwise working fuel pump.

I don’t know if this is practical or safe but you could test the hypothesis with a check valve along the fuel supply hose to the fuel rail. Or clamp the hose immediately after shutting off the engine then release it immediately before starting. Nah, get a fuel system pressure tester.

Sixto
98 E320s sedan and wagon

Just a thought...but if you changed the CPS, either from old to new or new to old, and it starts without issue...have you tried wiggling the connector on the CPS then starting it? It sounds Like the new start is a random condition. But the only constant that you wrote about was changing the CPS and it’s starting right up. Maybe the connection has gone bad?


Chris Dragotta
Benson, NC
1992 300D (Daily Driver)
1991 300D (The Backup)
1987?300SDL (The Parts Car)

So this is result. Fuel pump was the problem. This problem seemed like it was the crank position sensor, but it was not. I do not know why it starts when I change the sensor but it does. I ended up buying 3 sensors, relay, and bringing it to dealership for diagnosis total spent on these items $400. Wasted money. The thing to do is when the car wont start, test the pressure and if you don't get the 50 to 60 psi just change your fuel pump (left side). Cost of pump $270.00 and 30 min of your time. I change it on Saturday and it has been driving/starting perfect since then. I guess I can't flip on dealership for wrong diagnostic, but will say $1030.00 labor charge was their way of screwing me. THANK GOD for forums like this.